Downregulation of matrix metalloproteinases in hyperplastic dental follicles results in abnormal tooth eruption

Radiographic Features of Mandibular Second Molars with Eruption Disturbances: A Retrospective Study

We aimed to establish the characteristics and potential etiological risk factors of eruption disturbances in mandibular second molars (MM2). We retrospectively enrolled patients with eruption disturbances in MM2. A total of 143 MM2 with eruption disturbances from 112 patients (mean age 17.45 ± 6.35) were included in this study. Panoramic radiographs were employed to determine the risk factor, angulation type, impaction depth, tooth development stage, and associated pathology. The novel classification method of MM2 was based on impaction depth and angulation. Of 143 MM2, 137 and 6 were diagnosed with impaction and retention, respectively. Insufficient space was the most frequent risk factor for eruption disturbances. There were no significant differences between retention and impaction regarding sex, age, or side. The most frequent impaction type was Type I. The most frequent angulation of impacted MM2 was mesioangular. Impacted MM2 with shallower depth were more frequently associated with the presence of first molar undercut. Impaction types did not differ according to age, side, development stage, or distance from the MM1 distal surface to the anterior border of the ramus. Dentigerous cysts were associated with earlier MM2 development stages and greater MM2 depth. In conclusion, MM2 impaction types differed according to the risk factor, angulation type, MM1 undercut, and presence of cysts. Early MM2 development stage and greater MM2 depth were risk factors for MM2 eruption disturbances with cysts.

Revisiting the human dental follicle: From tooth development to its association with unerupted or impacted teeth and pathological changes

Dental follicles are involved in odontogenesis, periodontogenesis, and tooth eruption. Dental follicles are unique structures, considering that their remnants can persist within the jawbones after odontogenesis throughout life if the tooth does not erupt. Pathological changes may occur in these tissues as individuals age. The changes range from benign to life threatening. Thus, the assessment of age-related changes in dental follicles associated with unerupted teeth is of paramount importance. In this review, we summarize the physiological roles and changes in dental follicles in odontogenesis, tooth eruption, and aging, in addition to the pathological changes associated with these structures. We encourage investigators to consider this peculiar tissue as a unique model and explore its potential to clarify its importance from the viewpoints of developmental biology, tissue physiology, and pathology.

Effect of tetracyclines on pulpal and periodontal healing after tooth replantation: a systematic review of human and animal studies

Background

Pulpal and periodontal healing are two main concerns of delayed replantation of avulsed teeth. The objective of this review was to evaluate the effectiveness of topical and systemic application of tetracyclines on pulpal and periodontal healing after tooth replantation.

Methods

A comprehensive electronic search was conducted in six databases. This systematic review was carried out according to Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

Results

After exclusion of 246 irrelevant papers, 14 animal studies and one human study were included in this review. The human study showed that avulsed permanent teeth treated with doxycycline did not show a better clinical outcome for pulp and periodontal healing compared with treatment with normal saline. As for animal studies, significant more pulpal healing was observed in immature teeth treated with topical doxycycline in two researches, while another one study showed that there is no difference between teeth treated with normal saline and teeth treated with doxycycline. Systemic doxycycline exerted no significant effect on pulpal revascularization illustrated by one research. Only one out of four articles illustrated the positive effect of systemic tetracyclines on periodontal healing. One paper reported that intracanal application of demeclocycline promoted favorable periodontal healing. Two articles showed topical doxycycline contributed to favorable periodontal healing, while five studies showed no significant effect of topical tetracyclines on periodontal healing.

Conclusions

As a result of data heterogeneity and limitations of the studies, the effect of topical or systemic application of tetracyclines on pulpal and periodontal healing is inconclusive. More studies are required to get more clinically significant conclusions.

Multiple calcifying hyperplastic dental follicles: a major diagnostic consideration in multiple pericoronal lesions - report of two cases

Background

Pericoronal radiolucent lesions are a common radiographic finding, but it is rare that they occur in multiple forms. Multiple calcifying hyperplastic dental follicles (MCHDF) are entities with few cases described to date; nevertheless, they appear to have a very particular phenotypic pattern.

Cases presentation

Case 1: A 10-year-old male was evaluated radiographically, revealing four impacted canines, each accompanied by unilocular pericoronal radiolucency. Case 2: A 16-year-old male was planning orthodontic treatment; following his radiological evaluation all third molars were found to be accompanied with pericoronal radiolucencies. Enucleation, and third molar removal along with the pericoronal tissue were the respective treatments. Microscopically, in both cases, the specimens shown odontogenic epithelium, and type I and II calcifications in the hyperplastic follicles, all these characteristics were consistent with MCHDF.

Conclusion

Although MCHDF are a rare entity, they must be considered in the differential diagnosis of multiple pericoronal lesions. Under the light of the current evidence, the histological findings may be relatively heterogeneous, but their integration with both the clinical data, which are apparently particular, and with the radiographic characteristics, can lead to a definitive diagnosis.

Matrix Metalloproteinase-1 and Acid Phosphatase in the Degradation of the Lamina Propria of Eruptive Pathway of Rat Molars

The comprehension of dental pathogenesis and disorders derived from eruption failure requires a deep understanding of the molecular mechanisms underlying normal tooth eruption. As intense remodelling is needed during tooth eruption, we hypothesize that matrix metalloproteinase-1 (MMP-1) and acid phosphatase (ACP) play a role in the eruptive pathway degradation. We evaluated MMP-1-immunoexpression and the collagen content in the lamina propria at different eruptive phases. Immunohistochemistry and ultrastructural cytochemistry for detection of ACP were also performed. In the maxillary sections containing first molars of 9-, 11-, 13-, and 16-day-old rats, the birefringent collagen of eruptive pathway was quantified. MMP-1 and ACP-2 immunohistochemical reactions were performed and the number of MMP-1-immunolabelled cells was computed. Data were analyzed by one-way ANOVA and Tukey post-test (p ≤ 0.05). ACP cytochemistry was evaluated in specimens incubated in sodium β-glycerophosphate. In the eruptive pathway of 13- and 16-day-old rats, the number of MMP-1-immunolabelled cells increased concomitantly to reduction of collagen in the lamina propria. Enhanced ACP-2-immunolabelling was observed in the lamina propria of 13- and 16-day-old rats. Fibroblasts and macrophages showed lysosomes and vacuoles containing fragmented material reactive to ACP. MMP-1 degrades extracellular matrix, including collagen fibers, being responsible for the reduction in the collagen content during tooth eruption. The enhanced ACP activity at the mucosal penetration stage indicates that this enzyme plays a role in the degradation of remnant material, which is engulfed by macrophages and fibroblasts of the eruptive pathway. Therefore, enzymatic failure in the eruptive pathway may disturbs tooth eruption.

Dental Follicle Cells Participate in Tooth Eruption via the RUNX2-MiR-31-SATB2 Loop

Cleidocranial dysplasia (CCD) is characterized by the runt-related transcription factor 2 (RUNX2) mutation, which results in delayed tooth eruption due to disturbed functions of dental follicle. Accumulating evidence has revealed a key regulatory circuit, including RUNX2, miR-31, and special AT-rich binding protein 2 (SATB2) acting in concert in mesenchymal stem cell homeostasis and functions. However, whether such a regulatory loop works in dental follicle cells (DFCs) remains unknown. Herein, we investigated the roles of RUNX2-miR-31-SATB2 in DFCs from patients with CCD (DFCs-CCD) to advance our understanding regarding physical tooth eruption. We identified a novel mutation on exon 5 (c.634T>G, p.T212P) in RUNX2 via exome sequencing in the CCD patient with typical clinical presentations. Compared with DFCs from healthy donors, DFCs-CCD displayed significantly lower osteogenic, osteoclast-inductive, and matrix-degrading capacities and had lower RUNX2 (a transcriptional inhibitor of miR-31), higher miR-31, and downregulated SATB2. Lower ratios of RANKL/OPG and RANKL/RANK, as well as decreased expression of matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 2 (MMP2), would lead to inactivation of osteoclasts and suppression of bone matrix remodeling in DFCs-CCD. Furthermore, the roles of the RUNX2-miR-31-SATB2 loop in DFCs-CCD were revealed by endogenous miR-31 knockdown, which resulted in increased SATB2 and RUNX2, as well as osteoclast-inductive and matrix degradation capacities. Conversely, SATB2, RUNX2, MMP9, MMP2, and osteoclast-inductive factors expression declined upon ectopic miR-31 overexpression in normal DFCs. Importantly, neonatal mice with in vivo siRUNX2 delivery exhibited less activated osteoclasts around dental follicles and delayed tooth eruption. Together, these results suggest that RUNX2 mutation/haploinsufficiency disturbs osteoclast-inductive signaling in DFCs, which may be responsible for delayed tooth eruption in CCD patients. Manipulation of the RUNX2-miR-31-SATB2 loop may be a potential way to facilitate tooth eruption in CCD patients.

Soft tissue tooth impaction in a dog

Soft tissue impaction occurs when erupting teeth fail to penetrate the overlying gingiva. This has been attributed to abnormally dense, fibrous, gingival tissue. However, soft tissue tooth impaction has been reported in humans with histologically normal overlying gingiva and may be the result of a failure of normal breakdown of overlying tissue. This case report describes soft tissue impaction of multiple teeth in a dog with histologically normal overlying gingiva. The impactions were treated with multiple operculectomies that resulted in subsequent eruption of all impacted teeth.

Multiple calcifying hyperplastic dental follicles: A case report

This report describes a 31-year-old female patient with six impacted teeth. The crowns of the impacted teeth were surrounded with cyst-like lesions with a mixed internal structure and well-defined cortical borders. Microscopic examination of the specimen obtained from the follicle of the left mandibular third molar tooth revealed loose to moderately dense collagenous connective tissue with abundant calcified material and sparse epithelial islands. A diagnosis of multiple calcifying hyperplastic dental follicles was made.

Cisplatin and 4-hexylresorcinol synergise to decrease metastasis and increase survival rate in an oral mucosal melanoma xenograft model: a preliminary study

The present study was undertaken to examine the effects of cisplatin plus 4-hexylresorcinol (4-HR) combination therapy on oral mucosal melanoma (OMM) using cultured primary OMM cells in a tumour xenograft model. Cultured primary OMM cells were used for the MTT assay and DNA microarray. OMM cells were implanted into the submandibular glands of nude mice. The mice were then treated with cisplatin only or cisplatin plus 4-HR. Tumour size changes, survival rate and tumour metastasis were compared between the two groups by observation, micro-positron emission tomography (PET) and histological examination. In the MTT assay, the cisplatin plus 4-HR group showed significantly higher inhibition of OMM cell growth compared to the other groups (p<0.05). DNA microarray results showed significant inhibition of matrix metalloproteinase (MMP)-2 gene expression upon 4-HR application. The necropsy and micro-PET results showed that the mice from the cisplatin-only group had more distant metastases than the mice from the cisplatin plus 4-HR combination group (p=0.002). MMP-2 expression was lower in the primary tumours in the cisplatin plus 4-HR combination group than in the cisplatin-only group (p<0.001). Overall survival was longer in mice from the cisplatin plus 4-HR combination group than in the cisplatin-only group (p=0.049). In conclusion, the combined effect of cisplatin and 4-HR resulted in fewer metastases and longer survival than cisplatin-only treatment in the OMM xenograft model.

Therapeutic targeting of oncogenic transforming growth factor-β1 signaling by antisense oligonucleotides in oral squamous cell carcinoma

The transforming growth factor-β1 (TGF-β1) signaling pathway is important in human oral squamous cell carcinoma (OSCC). Accordingly, the aims of this study were to evaluate the effect of antisense TGF-β1 oligonucleotides (ODNs) on OSCC in cell culture and in a xenograft model, as well as to evaluate any effects ODNs have on proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase-2 (MMP-2) expression in the xenograft model. We performed real-time cell electronic sensing (RT-CES) to determine the effect of antisense TGF-β1 ODNs on SCC-9 cell growth. To examine the in vivo effect of antisense TGF-β1 ODN therapy, SCC-9 cells were grafted into nude mice. Antisense ODNs were injected into the mass daily. Tumor size, body weight and duration of survival were assessed daily. Specimens from the main mass were used for immunohistochemical staining to analyze PCNA and MMP-2 expression. In vitro treatment with antisense TGF-β1 ODNs decreased TGF-β1 expression and growth of SCC-9 cells. In the xenograft model, the antisense TGF-β1 ODN group exhibited a significantly decreased tumor growth rate compared to the control, which received Dulbecco's modified Eagle's medium (DMEM) (P=0.022). However, mean survival time and body weights were not significantly different between the groups (P>0.05). Immunohistochemistry showed that tumors from animals that received antisense TGF-β1 ODNs had significantly lower expression levels of PCNA and MMP-2 compared to tumors from animals in the DMEM group (P<0.05). In conclusion, antisense TGF-β1 ODN therapy significantly inhibits tumor growth compared to controls, however, there are no significant differences between groups with respect to changes in body weight.

Case report: Unclassified syndrome involving dental enamel, dentine and lack of tooth eruption

BACKGROUND

Regional odontodysplasia, also described as ghost teeth, has been described on a number of occasions, in some cases generalized odontodysplasia affecting both the primary and the permanent dentition. However, generalised odontodysplasia is a very rare finding, involving large pulps and short roots of the whole dentition and in the cases previously reported the teeth finally erupt. In the case reported on herein this has not happened.

CASE REPORT

A female patient, now aged 22-years-old, cared for in the TAKO-centre (Oslo) since she was 5 years old, presented with a continuing problem of absence of permanent teeth due to total lack of eruption. All her permanent teeth were either retained intra-alveolar or had been extracted following previous periods of pain and infections. There was no enamel on any of the permanent teeth and the dentine was softer than normal. In addition, there appeared to be very little potential for eruption. Hence, tooth development was affected in all aspects. Her skeletal height was much shorter than expected taking her tall parents into consideration. After all possible assessments, no specific diagnosis for the condition of this young woman has been determined.

TREATMENT

Before the present series of dental care the patient was wearing full dentures in both jaws. In the autumn of 2007, implants were placed in her maxilla and an implant supported fixed prosthesis in porcelain was installed the following spring. Similarly, implants were placed in her mandible, partly in retained teeth, in the autumn of 2008, and an implant supported fixed prosthesis was inserted during the spring of 2009.

FOLLOW-UP

after prosthetic treatment a dental hygienist has seen the patient regularly. No problems or signs of infections have occurred to date.

CONCLUSION

This case report concerns a rare and apparently un-named syndrome affecting both primary and permanent teeth. This paper has been written with an aim of gathering the views as to the aetiology of her problem, hopefully finally to provide a definitive diagnosis.

Static tensional forces increase osteogenic gene expression in three-dimensional periodontal ligament cell culture

Orthodontic tooth movement results from the combinational process of both bone resorption and formation in the compressive and tension sides, respectively. However, the genes responsible for new bone formation in tension sides have not been determined. In this study, we used DNA microarray and real-time RT-PCR to identify genes in human periodontal ligament (PDL) cells that undergo significant changes in expression in response to static tensional forces (2 or 12 hours). The genes found were alkaline phospatase (ALP), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and several collagen genes. Furthermore, an ELISA evaluating the expression of VEGF, type IV collagen and MMP-2 found levels significantly increased after 24 and 72 hours (P 0.05). ALP activity was also increased after 24 hours (P 0.05). Collectively, we found the genes up-regulated in our study by the static tensional force are related to osteogenic processes such as matrix synthesis and angiogenesis.